1. Field of the Invention
The present invention relates in general to a system for applying closures to containers and, more particularly, to a method and apparatus for sealing a container by applying a closure and a seal membrane to the container neck.
2. Description of the Related Art
Many closure systems include a cap and a foil liner sealing the neck opening to preserve the freshness of the product and provide visual evidence that the container has not been previously opened. The underside of the foil seals are usually provided with a substance such as an adhesive or a polymer coating which adheres the liner to the container neck when the substance is activated by induction heating or other means. Preferably, the foil disc is adhered to the entire circumference of the neck so that the container is completely sealed by the liner.
The foil seal disc may be applied to the neck before the closure, with the foil disc being pressed against the lip by an applicator during activation of the adhesive or other suitable substance. By evenly pressing the seal against the lip during application, an effective seal may be obtained around the entire circumference of the neck. After the neck is sealed with the foil disc, the closure is applied in a separate step as is known in the art. Although applying the seal and cap in separate steps may be used to obtain an effective seal between the foil disc and the neck, this method is time consuming and inconvenient.
Positioning the foil disc in the closure prior to application allows the disc and the closure to be simultaneously applied to the container neck. The closure is seated on the neck using known capping techniques. When the closure is fully seated on the neck, the top of the closure holds the foil disc against the lip of the container neck. The adhesive or other substance is activated to adhere the disc to the neck. The effectiveness of the seal between the foil disc and the lip around the neck circumference depends in part on whether the foil disc is uniformly held against the neck by the cap when the seal is attached to the neck. If the cap is orientated at an angle relative to the neck, the closure may not apply sufficient pressure to obtain an effective seal around the circumference of the foil disc. For threaded closure systems, the final position or height of the cap may vary depending upon the initial orientation of the cap threads relative to the neck threads. At the upper end of this height range, where the cap is not fully tightened onto the container neck, a gap may be introduced between the underside of the cap top and the lip. This gap may prevent the cap from applying sufficient force to press the foil seal against the neck. As a result, the foil seal may be only partially adhered to the neck or, in some instances, the foil disc may not be attached at all to the foil disc.
This invention provides a system for sealing a container with a foil disc and the like. The closure and foil disc are simultaneously positioned on the container neck, improving the efficiency of the capping process. With the method and apparatus of this invention, the liner disc is securely held against the lip of the container neck during activation of the adhesive or other suitable substance to promote the formation of an effective seal. The present invention offers considerable advantages over prior structures as is evident from the description of the related art and the following description of the invention.